The invention discloses a double-break vacuum circuit breaker. The circuit breaker comprises an upper arc extinguishing chamber, a lower arc extinguishing chamber and a transmission box, wherein the upper arc extinguishing chamber and the lower arc extinguishing chamber are vertically arranged, a three-linkage device is arranged in the transmission box and comprises an upper transmission plate and a lower transmission plate, the left end of the upper transmission box and the left end of the lower transmission box are hinged by a first hinge shaft, the right end of an insulation pull rod is connected onto the first hinge shaft, an upper movable conductive element at a movable end of the upper arc extinguishing chamber is hinged with the right end of the upper transmission plate by an upper hinge shaft, the movable end of the lower arc extinguishing chamber is hinged with the right end of the lower transmission plate by a lower hinge shaft, an upper guide long groove, a lower guide long groove and a first guide long groove are arranged on the transmission box, the upper guide long groove is used for guiding the vertical movement of the upper hinge shaft, the lower guide long grieve is used for guiding the vertical movement of the lower hinge shaft, and the first guide long groove is used for guiding the horizontal movement of the first hinge shaft. By arranging the upper guide long groove, the lower guide long groove and the first guide long groove, the constraint to the upper transmission plate and the lower transmission plate is increased, the moving synchronism is improved, and the upper arc extinguishing chamber and the lower arc extinguishing chamber are ensured to be simultaneously disconnected.